Electrowetting display devices may comprise electrowetting display elements, wherein an oil layer covers a display area of a particular display element when that display element is in an off state, and wherein the oil layer is retracted so as to cover less of the display area when the display element is in an on state. In particular, to switch the display element to the on state, a voltage is applied to an electrically conductive fluid via an electrode, the electrically conductive fluid being in contact with, but immiscible with, the oil. To switch the display element to the off state, the voltage is switched off.
Light incident upon the display element may generate current inside a semiconducting channel of a thin film transistor. It is desirable to reduce this effect.